Russian President Vladimir Putin has said the downing of a Russian military plane by Syrian air defences was the result of a "tragic chain of circumstances", in an apparent effort to calm tensions after his country’s defence ministry accused Israel of "hostile" actions.

The downing of the jet late on Monday night highlighted the dangers posed by the conflicting interests of various powers in the crowded skies over war-torn Syria and threatened to damage relations between Russia and Israel.

The incident was also the worst case of friendly fire between Russia and Syria, since Moscow's military intervention in the country in support of President Bashar al-Assad's forces in September 2015.

The Russian military said the Il-20 electronic intelligence plane was hit 35km off Syria's Mediterranean coast as it returned to its home base nearby. All 15 Russian crew members were killed.

Russian defence officials described manoeuvres by Israeli fighter jets during the incident as "hostile" and said it had a right to retaliate.

"The Israeli pilots were using the Russian aircraft as a shield and pushed it into the line of fire of the Syrian defence," Igor Konashenkov, Russian defence ministry spokesperson, told state media.

A warning from Israel was received "less than one minute before the strike, which left no chance for taking the Russian plane to safety," added Konashenkov.

But Putin later struck a more conciliatory tone, telling reporters the shooting down of the plane was the result of a "chain of tragic and chance circumstances".

"As for retaliatory measures, they will be aimed first and foremost at further ensuring the safety of our military personnel and facilities in Syria. And these will be steps that everyone will notice," Putin said.

It was a different situation when a Turkish jet shot down a Russian fighter jet on the Syrian border three years ago, according to the Russian president. "The Turkish fighter jet shot down our plane on purpose," he said.

Earlier in the day, the Israeli military rejected claims its fighter jets had indirectly caused the incident and said it holds Syria, Iran and Lebanon's Hezbollah responsible for it.

It confirmed it "targeted" a Syrian military facility the Israeli military said was about to transfer weapons to Hezbollah on behalf of Iran, a major ally of Syrian President Bashar al-Assad.

But it insisted the Russian plane had been felled by "extensive and inaccurate" Syrian anti-aircraft fire, adding anti-air batteries "did not bother to ensure that no Russian planes were in the air".

By the time the Russian plane was hit, the Israeli jets were already out of Syria and back in their own airspace, Israel's army added.

There was no immediate word from Syria's government.

For his part, Israel's Prime Minister Benjamin Netanyahu quickly called Putin to express sorrow over the death of the plane's crew, blamed the plane's loss squarely on Syria and offered to send Israel's air force chief to Moscow to share information about the incident.

According to Netanyahu's office, the Israeli leader said his country would keep acting against Iran in Syria.

Putin told Netanyahu that the Israeli raid violated Syria's sovereignty and breached the Russian-Israeli de-confliction agreement. He urged the Israeli side "not to allow such situations to happen again", according to the Kremlin.

'Serious restrictions'

Since intervening in Syria's war, Russia has generally turned a blind eye to Israeli attacks inside the country.

Israel has carried out about 200 air raids in the last two years, according to Israeli officials.

For several years, Israel and Russia have maintained a special hotline to prevent their air forces from clashing in the skies over Syria. Israeli military officials have previously praised its effectiveness.

A dispute between Israel and Russia could restrict Israel's ability to mount air raids inside Syria on what it considers the greatest threat to its security from the Syria conflict: the build-up of Iranian forces or Iranian-backed Hezbollah fighters.

Sima Shine, a former senior Mossad official and ex-deputy director-general at Israel's strategic affairs ministry, told Israel's Army Radio station the downing of the plane was problematic for many reasons.

"I think it will impose very serious restriction on Israel's freedom of activity," she said.